arisvega writes: Some 400 high-tech South African traffic lights are out of action after thieves in Johannesburg stole the mobile phone SIM cards they contain. JRA (Johannesburg Road Agency) said it is investigating the possibility of an "inside job" after only the SIM card-fitted traffic lights were targeted.

The cards were fitted to notify JRA when the traffic lights were faulty.

JRA believes a syndicate "with links on the inside" is behind the thefts.

"We have 2,000 major intersections in Johannesburg and only 600 of those were fitted with the cards," the agency's spokesperson Thulani Makhubela told the BBC.

"No-one apart from JAR and our supplier knows which intersections have that system."

The thieves ran up bills amounting to thousands of dollars by using the stolen cards to make calls.